Broadly stated, the timpanist has two choices when choosing what type of timpani head they will use on each set of drums, that of natural skin (calf or goat), or plastic. Of the natural skins, calf is by far the more popular and common, but goat skin is an alternative which some timpanists prefer for its sound and also the tradition of this sound. There are also two styles of plastic timpani head, that of the “Renaissance” skin (made by Remo - Evans Strata heads also fall into this category), which seeks to emulate the sound of natural skin without some of the hazards entailed in the use of calf or goat skin, and also the older style of white plastic head. Conductors may make a particular request, which is almost always for calf skin, but the choice ultimately lies with the musician.

‘The calf and the goat skin were considered for a long time of equal quality and were sufficient for the requirements. The fact that the choice fell rather on one as on the other was because of the fact that in the appropriate regions more calves than goats were bred.’[1] - Dieter Dyk

For thousands of years the skins of newborn animals have been used as the material which forms the head of a drum. In time the call arose for skins of higher quality, of more uniform thickness, and above all capable of producing and sustaining a clear note such as is expected from a timpani head. The original, untreated calf skins were rich in tone but could not produce this richness in their upper and lower register. A technique known as polishing, or sharpening, improved the sound qualities of the skins but now gave them that property of calf skin known and battled with around the world : a susceptibility to changes in temperature and humidity. An early method to combat this was limewashing, but not surprisingly it had an unfavourable effect on the sound quality. Again the skins were subjected to a new process, called splitting, which produced very even skins, but also very thin; the lime particles were now unable to bond with the natural material. Lime was replaced by water repellent glycerin and it is this process which forms the basis of the ubiquitous Kalfo calf skin timpani head. [2]

For all these techniques and processes, aimed at making the calf skin less susceptible to the weather but still possessing of a full and clear tone, still today only a compromise between problems of weather and strength of sound has been achieved; the plastic skin was developed as an alternative approach to these problems. But the plastic skin is a relatively new invention, less than 50 years old, so most of the repertoire of a symphony orchestra was written for the sound of natural skin. However calf skin is not used solely for reasons of tradition, but because its properties give it a sound that timpanists in many orchestras prefer over any other.

Louis Sauvetre : ‘I definitely don’t play the same when I play calf heads. I think it is more easy to fit in the sound of the orchestra, to play more deep, to find more colours with one pair of sticks only. Especially the contact with the head is very different.’

Many players speak of the superior sound quality of the calf skin and its many favourable characteristics, such as its clearer rhythmic and articulation qualities, its capabilities across the entire dynamic range – a full, strong tone in fortissimo but also clarity and projection in pianissimo (plastic skins in comparison often only sound good in a narrower range of dynamics), and also more subjective qualities which are difficult to describe in words, such as an ability to blend with the other timbres of the orchestra, and also the range of colours and sonorities which the skin itself is capable of producing, saving the player from constantly changing mallets in order to achieve these results.

Didier Benetti (Orchestre National de France): ‘The after-effect [of calf skin, as compared to plastic skin] is shorter, but it sounds good and blends better with the orchestral sound … the rhythm is clearer, the natural skins respond better to harder playing. On the plastic skins one must play often hard, so that it is at all audible in the hall.’ [4]

Dieter Dyk : ‘It [calf skin] even in very loud passages – played with felt or flannel – keeps a certain quality (not with the wood stick). The goat skin is not reacting to felt as clear as the calf. With goat you use harder (flannel) sticks.’

As mentioned earlier, both of the natural skins are affected strongly by the surrounding temperature and humidity (but calf more so than goat). Heat or dryness shrinks the skin, cold or wet conditions cause it to loosen, so the drum cannot be relied upon to always hold its pitch. It is not only during outdoor performances that these problems are faced, excess heat from stage lights or dry air from the air-conditioning system are common problems in many concert halls. In a freezing church the skin might be expected to slacken because of the extreme cold, but instead the dry air causes the pitch to go up! Despite this, many timpanists will take these risks with calf skin because the resulting sound is worth these problems.